Are you sure? Because I haven't found any text stating that.

Alduin is the Nordic version of the god of time. Auri-El is the elven version of the god of time. These are two aspects of the same Aedric spirit, just given different names and adapted for different religions.

When Allesia won her rebellion and defeated the Aylieds, she did so with the assistance of Nords from Skyrim. (Note: Not all of Tamriel's Men are descendants of Atmora, there were aboriginal tribes already in Cyrodil, Blackmarsh, and other places.) The tribesman she commanded worshiped elven gods, because that is all they knew. THe Nords, on the other hand, worshiped their own gods. In order to unite the two people under a common cause, she "invented" the diety Akatosh, who shared characteristics of both Alduin, and Auri-El. Due to the pact she made with Alduin/Auri-El, the Imperial people's faith in the diety, and several dragon-breaks, Akatosh was given an actual form/personality in the being that is Alduin/Auri-El.

So Akatosh/Alduin/Auri-El are all the same schizophrenic spirit, although most likely the Akatosh aspect was destroyed during the Oblivion Crisis, allowing the more violent and threatening Alduin aspect to escape.

As for the Septims being dragonborn. Tiber Septim was dragonborn, with a dragon soul. The rest of his line was not. When it is stated that they have "dragon-blood flowing through their viens" it simply means they have Septim blood flowing through their viens, because Tiber Septim was "the dragon". Perhaps Septim blood holds some magical property not found in other lineages, as they are often able to scry fate and are anointed by Aedra for various purposes.

The Amulet of Kings is an Aylied soulgem, called the Chim-el Abadal, and house the souls of all those who made the pact with Akatosh over the years. Supposedly it requires an individual to have "dragonblood" in their veins to wear it, although it seems to have more to do with the quality of the soul of the wearer. Martin was appointed by the aedra to stop the OC, while Mankar Cameron was appointed to begin it (either by aedra or daedra). The CoC had no reason to wear the amulet; if he could it would void Martin's role in the event. Therefore, the CoC could not.

Sorry for the wall o' text. I like lore.



Uh...thanks?

Sure, there are plenty of texts full of inconstancy that prove just that. The very premises of the pact of Akatosh's pact with Alessia and keeping the boundries of Oblivion is bull because it specifically states "As long as you and your decendents.. ware this amulet.." and Tiber and the Septim line is not even relatives of Alessia, nor was Reman.

But the fact is still that it worked. It did keep the boundries of Oblivion. And who said that "decendants" is of blood and not of spirit?